After reading the several discussions about CTs with clogged gas cap vents I decided to look at mine more closely. It was plugged!! I removed the rubber seal and poured the center depression full of mineral spirits. 10 minutes later the center depression was still full. Next I submerged the entire cap in mineral spirits for 2 hours. Pull the cap out, fill the center depression again and it promptly drained out the vent hole. Blow it out with the air compressor (wearing safety face shield), apply a bit of oil to prevent rust, and reinstall the rubber seal. No drilling required, this was an easy project.